OncoGenex Pharmaceuticals has announced the preliminary results from a Phase 2 study of its investigational compound OGX-427, designed for the treatment of chemotherapy-naive patients with metastatic castrate-resistant prostate cancer (mCRPC).
OGX-427 acts by inhibiting the production of Hsp27, a cell-survival protein expressed in various cancers, including prostate, bladder, breast and non-small cell lung cancer.
The Phase 2 study included 32 patients, of which 17 patients were randomised to OGX-427 plus prednisone, while the remaining 15 patients received prednisone alone.
The study reported that OGX-427 plus prednisone showed a higher number of patients without disease progression at 12 weeks, greater declines in prostate-specific antigen (PSA) and circulating tumor cells (CTC) compared to patients receiving prednisone alone.
Following 12 weeks of treatment, 71% of patients in the OGX-427 plus prednisone arm were progression-free and 76% experienced an overall decline in PSA compared to 33% and 53% respectively in the prednisone alone arm.
In the trial, the primary efficacy endpoint is defined as the proportion of patients without disease progression at 12 weeks, which is determined by PSA levels, measurable disease, bone lesions, global deterioration or requiring palliative radiation therapy.
Primary investigator of the study, Kim Chi, said: "The PSA declines, progression free survival at 12 weeks, and response rates observed thus far are supportive of OGX-427’s ability to suppress androgen receptor activity and tumor cell survival through inhibition of Hsp27."
The drug-related infusion reactions that occurred were grade 1 or 2 chills, nausea, vomiting, flushing, diarrhoea, fatigue, dizziness, decreased appetite and pyrexia.
The findings from the study will be presented in conjunction with the American Society of Clinical Oncology (ASCO) 2012 Genitourinary Cancers Symposium in San Francisco, US.
The company also plans to commence a Phase 2 study of OGX-427 in combination with Zytiga (abiraterone) in castrate-resistant prostate cancer patients.
OncoGenex is a biopharmaceutical company focused on the development and commercialisation of new cancer therapies.
Image: Micrograph of prostate adenocarcinoma, acinar type, the most common type of prostate cancer. Photo: Nephron.